300 
EDGAR NELSON TRANSEAU 
Belongs near Oe. spirale Hirn, from which it differs in being gynan- 
drous, in having narrower and longer vegetative cells, swollen suffultory 
cells. Occurs in the Gray ponds southeast of Lerna, Illinois. Type 
in herb. E. N. T. Collections No. 1361, 1364. Plate XXIX, figures 
6-8. 
Oedogonium pauco-costatum nov. sp. 
Oedogonium dioicum, macrandrium ; oogoniis singulis, ellipsoideis, 
opercula apertis, circumscissione superiore; oosporis ellipsoideis, 
oogonia fere complentibus, membrana triplici: episporio, in latere 
exteriore, laevi, mesosporio longitudinaliter costato, costis integris, 
interdum anastomosantibus, in medio oosporae c : a 15-19; antheridiis 
2-8-cellularibus ; spermatozoidis binis, divisione horizontali ortis; 
cellula fili terminali obtusa, cellula basali forma, ut vulgo, elongata; 
crassit. cell, veget. plant, fern (15-) 20-27 yu, altit. 70-155^1; 
crassit. cell, veget. plant, masc. . . (15-) 19-25 fx, altit. 70-160^1; 
crassit. oogon 54-60 ^^, altit. 70-104 jx; 
Dioecious, macrandrous, oogonia single, ellipsoid, opercula te, divi- 
sion superior; oospore elliptical nearly filling the oogonium, membrane 
triple: outer wall smooth on the outer side, median wall longitudinally 
ribbed, ribs from 15-19 in number, inner wall smooth; antheridia 
2-8-celled; sperms two, division horizontal; terminal cell obtuse, basal 
cell usually elongate ; 
diam. veg. cells, female fil. . ..... (15-) 20-27 }x, length 70—155 /x; 
diam. veg. cells, male fil (15-) 19-25 n, length 70-160^1; 
This species is near Oedogonium Australicum Hirn, but differs in 
being larger in most dimensions, in having elliptical instead of globose- 
elliptical spores, and in having a smaller number of ribs on the median 
spore wall. It has been recorded only from the Ice Plant pond, Casey, 
Illinois, where it was associated with Oe. praticolum (described above) 
and Oe. taphrosporum Nordst. and Hirn. during July, 1912. Type in 
herb. E. N. T. Collection No. 1495. Plate XXVIII, figure 5. 
crassit. oospor.-. .... 
crassit. cell, antherid, 
50-56 n, altit. 66- 90 m; 
18-23 M, altit. 8- 12 fjL. 
diam. oogonia 
diam. oospores 
diam. antheridial cells 
54-60 )U, length 70-104^1; 
50-56 /X, length 66- 90^t; 
18-23 /JL, length 8- 12 At. 
Normal School, 
Charleston, III. 
